Abstract: In order to investigate the aerodynamic performance of over–under turbine-based combined-cycle (TBCC) propulsion systems over the entire range of the vehicle’s Mach number， a TBCC exhaust system was subjected to computational study in full flight envelop. Steady-state wind tunnel experiments of the exhaust nozzle under typical flight conditions were carried out to validate the reliability of numerical simulation method. Flow-field structures and the wall pressure distributions were obtained and were compared with the computational results. Results indicate that flow structure of the TBCC exhaust system is complicated because the two exhaust jet streams interact with each other around the exit plane of the turbo. Optimizing geometrical parameters of the TBCC exhaust system can reduce the effects of interaction on the whole flow-field structure and thrust performance. In full flight envelop， the total thrust coefficient of the exhaust system is all higher than 0.9. The thrust performance of ramjet is relatively poor at low Mach number because of a large area of flow separation， but it has little influence on the exhaust system thrust performance. The CFD simulation results which include wall pressure distributions and wave structures of flow field agree well with the experimental data， which demonstrated that the CFD methods are effective in evaluating the aerodynamic performance of the TBCC exhaust system.

Key words: Numerical simulation; Wind tunnel experiment; Flow-field structure; Thrust performance

摘要： 为探索并联TBCC排气系统在宽马赫数飞行范围内的性能变化规律，针对某TBCC排气系统构型开展了飞行包线内的数值模拟分析。为验证数值模拟方法的可靠性，对该实验模型完成了典型工作点静特性风洞实验，获得了相应的流场结构和壁面压力分布规律，并将实验结果与数值模拟结果进行了对比。研究结果表明:并联TBCC排气系统双通道气流在涡轮下壁面出口处发生严重干扰导致出口流场复杂。优化设计TBCC排气喷管，有利于降低气流干扰对整个排气系统流场结构和推力性能的影响；飞行包线内，排气系统总的推力系数均高于0.9。气流大面积分离导致冲压发动机低马赫数时性能较低，但其对排气系统整体的推力性能影响很小；数值模拟得到的壁面沿程压力分布、流场波系结构等均与实验结果非常吻合，因此，数值计算结果用来评价TBCC排气系统性能的可靠性得到实验验证。

关键词: 数值模拟；风洞试验；流场结构；推力性能